Temperature determining device and process

• US 6,379,038 B1
• Filed: 06/21/1999
• Issued: 04/30/2002
• Est. Priority Date: 06/22/1998
• Status: Expired due to Term

• Current Assignee: Ralph A. Felice
• Original Assignee: Ralph A. Felice
• Inventors: Felice, Ralph A.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Gonzalez, Madeline
• Application Number:
  US09/337,705
• Time in Patent Office: 1,044 Days
• Field of Search: 374/101, 374/102, 374/103, 374/121, 374/126, 374/9, 374/128, 250/338.1, 702/130
• US Class Current: 374/128
• CPC Class Codes: G01J 5/0003 for sensing the radiant heat transfer of samples, e.g. emittance meter
• CPC Class Codes: G01J 5/60 using determination of colour temperature

Abstract

The present invention relates to a device useful for the measurement of the temperature of a radiating body. More particularly, the present invention relates to a radiation pyrometer that detects and compensates for emissivity that changes with wavelength, as in metals. Additionally the present invention relates to a device that enhances the resolution and repeatability of the measured temperature of the radiating body. Additionally, the present invention relates to the technique utilized to enhance the resolution and repeatability of the measured temperature.

Claims

1. A process for measuring the temperature of a radiating body, comprising:

a) quantifying the radiation intensity emitted by a radiating body at no less than 4 distinct wavelengths;

b) generating a mathematical function which represents said quantified radiation intensities at the corresponding wavelength at which said radiation intensity was quantified;

c) selecting no less than two specific wavelengths;

d) generating a spectral intensity using said mathematical function for each of said wavelengths;

e) generating an individual two-wavelength temperature value of said radiating body utilizing the radiation equation $T_{12}=\frac{C^{\mathrm{\prime <br><br>}}<br><br>\left(1/{\mathrm{\lambda <br><br>}}_1-1/{\mathrm{\lambda <br><br>}}_2\right)}{\ln <br><br>\text{\hspace{1em}<br><br>}<br><br>R-5<br><br>\text{\hspace{1em}<br><br>}<br><br>\ln <br><br>\left({\mathrm{\lambda <br><br>}}_2/{\mathrm{\lambda <br><br>}}_1\right)}$

 

where T₁₂=individual two-wavelength temperature,

λ

₁,λ

₂, . . . λ

_n=specific wavelengths selected,

C′

=second radiation constant, and

R=ratio of the generated spectral intensity I₁, calculated using said mathematical function at λ

₁, to the generated spectral intensity I₂, calculated using said mathematical function at λ

₂;

f) analyzing said individual two-wavelength temperatures for consensus or lack of consensus;

g) if there is consensus, reporting the temperature and ending the process;

h) if there is no consensus, analyzing said individual two-wavelength temperatures for spectrally varying emissivity;

i) calculating the functional dependence of emissivity on wavelength for said radiating body from said two-wavelength temperatures;

j) calculating new individual two-wavelength temperatures using said functional dependence of emissivity on wavelength; and

k) reporting the average of said new individual two-wavelength temperatures.

2. The process of claim 1, wherein said selection step comprises selecting no less than three specific wavelengths;

and wherein said generating an individual two-wavelength temperature value step comprises generating an individual two-wavelength temperature value of said radiating body utilizing said radiation equation for each pair of said specific wavelengths selected and said spectral intensity generated utilizing each of said specific wavelengths.

3. The process of claim 2, wherein only said quantified radiation intensity which exhibits emission spectra consistent with known thermal radiation effects is utilized for generation of said mathematical function.

4. The process of claim 2, wherein said generated spectral intensities are utilized to generate said two-wavelength temperatures at wavelengths at which said quantified radiation intensities exhibit fractional residuals no less than −

0.1 and no more than 0.1.

5. The process of claim 2, wherein said generated spectral intensities are utilized to generate said two-wavelength temperatures at wavelengths at which the fractional residuals of said quantified radiation intensities exhibit an RMS value substantially equal to zero.

6. The process of claim 2, wherein a measured temperature value is generated by the averaging of said individual two-wavelength temperature values generated for every pair of said specific wavelengths and said spectral intensities.

7. The process of claim 1, wherein step f) comprises inspecting said individual two-wavelength temperatures for standard deviation in excess of an acceptable level.

8. The process of claim 7, wherein said acceptable level is less than about 0.25% of the absolute temperature.

9. A process for measuring the tolerance of the measured temperature of a radiating body, comprising

a) measuring the temperature according to claim 8, and

b) calculating the statistical variation of said individual two-wavelength temperature values generated utilizing said radiation equation, no less than three said specific wavelengths, and said spectral intensities generated utilizing each of said specific wavelengths.

10. The process of claim 9, wherein said statistical variation is the standard deviation of said measured temperature value.

19. A process for measuring the spectral emissivity of a radiating body, comprising

a) measuring the temperature according to claim 8, and

b) calculating said spectral emissivity using the expression $\varepsilon$

=Hλ



λ

5

[

hc/λ

KBT-1]2

hc2

 

where H_λ

=the radiation quantified,

ε

=the emissivity,

T=said measured temperature,

h=Planck'"'"'s constant,

c=the speed of light,

λ

=the wavelength of the radiation, and

k_B=Boltzmann'"'"'s constant.

11. A temperature measuring device, comprising:

a) an optical input system which receives a portion of the emitted radiation of a radiating body;

b) a wavelength dispersion device which separates said emitted radiation according to wavelength;

c) a transducer which senses said separated radiation and provides a quantified output corresponding to radiation intensity for each wavelength of said emitted radiation;

d) means for generating a mathematical function to represent said quantified output of said radiation transducer as a function of wavelengths;

e) means for selecting no less than two specific wavelengths;

f) means for generating a spectral intensity value at each said selected specific wavelength, utilizing said mathematical functions and

g) means for generating an individual two-wavelength temperature value utilizing no less than two said spectral intensity values and the radiation equation $T_{12}=\frac{C^{\mathrm{\prime <br><br>}}<br><br>\left(1/{\mathrm{\lambda <br><br>}}_1-1/{\mathrm{\lambda <br><br>}}_2\right)}{\ln <br><br>\text{\hspace{1em}<br><br>}<br><br>R-5<br><br>\text{\hspace{1em}<br><br>}<br><br>\ln <br><br>\left({\mathrm{\lambda <br><br>}}_2/{\mathrm{\lambda <br><br>}}_1\right)}$

 

where T₁₂=individual two-wavelength temperature,

λ

₁,λ

₂, . . . λ

_n=specific wavelengths selected,

C′

=second radiation constant, and

R=ratio of the generated spectral intensity I₁, calculated using said mathematical function at λ

₁, to the generated spectral intensity I₂, calculated using said mathematical function at λ

₂;

h) means for analyzing said individual two-wavelength temperatures for consensus or lack of consensus;

i) means for calculating the functional dependence of emissivity on wavelength for said radiating body;

j) means for calculating new individual two-wavelength temperatures using said functional dependence of emissivity on wavelength; and

k) means for reporting the average of said new individual two-wavelength temperatures.

12. The device of claim 11, wherein said generating an individual two-wavelength temperature value step comprises means for generating a two-wavelength temperature value of said radiating body utilizing said radiation equation for each pair of no less than three specific wavelengths and their corresponding spectral intensities generated utilizing said mathematical function.

13. The device of claim 12, wherein only said quantified output corresponding to radiation intensity which exhibits emission spectra consistent with known thermal radiation effects is utilized for generation of said mathematical function.

14. The device of claim 12, wherein said spectral intensities are generated at wavelengths at which said quantified output corresponding to radiation intensity exhibits fractional residuals no less than −

0.1 and no more than 0.1.

15. The device of claim 12, wherein said spectral intensities are generated at wavelengths at which the fractional residuals of said quantified output corresponding to radiation intensity exhibit an RMS value substantially equal to zero.

16. The device of claim 12, wherein a measured temperature value is the average of said two-wavelength temperature values generated utilizing said radiation equation.

17. The device of claim 16, further comprising the determination of the tolerance of said measured temperature value by calculating the statistical variation of said two-wavelength temperature values.

18. The device of claim 17, wherein said statistical variation is the standard deviation of said average.